Gas generator

ABSTRACT

A gas generator ( 10 ) comprises an outer housing, which has at (east two housing parts ( 12 ), which are connected to each other, in the form of a diffuser bowl ( 14 ) with outflow openings ( 16 ) towards the outside and a cover ( 20 ) directly connected to the diffuser bowl ( 14 ). Inside the gas generator ( 10 ), at least one first and one second combustion chamber ( 30, 36 ) are provided, wherein the first combustion chamber ( 30 ) is delimited by an inner wall ( 32 ) and the second combustion chamber ( 36 ) is located within the space delimited by the diffuser bowl ( 14 ) and the cover ( 20 ). The diffuser bowl ( 14 ) and/or the cover ( 20 ) comprise a section ( 24 ) that is shaped, in particular deep-drawn, into an indentation, forming at least partially a circumferential section of the inner wall ( 32 ).

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/129,442, filed on May 16, 2011, which corresponds toPCT/EP2009/008422, filed Nov. 26, 2009, and which claims the benefit ofGerman Application No. 10 2008 060 305.8, filed Dec. 3, 2008, thesubject matter of which is incorporated herein by reference in theirentireties.

BACKGROUND OF THE INVENTION

The invention relates to a multi-stage inflator, especially for avehicle occupant restraint system in motor vehicles.

From the state of the art multi-stage inflators comprising an outerhousing are known which includes substantially two housing shellsconnected to each other and defining an interior which forms, interalia, a main combustion chamber. In the main combustion chamber pluralsleeve-shaped components are provided which may be in the form ofseparate additional combustion chambers. The plurality of componentssuch as e.g. the separate combustion chamber elements, igniter sleevesand igniter carriers, render the assembly complicated and thusexpensive. The use of housing shells permits simple and inexpensivemanufacture and assembly as well as a light-weight design of the outerhousing. The outer housing must be extremely loadable when the inflatoris ignited.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a multi-stage inflatorhaving a reinforced mechanical structure and a simplified and thusinexpensive design.

This object is achieved by an inflator according to the inventioncomprising an outer housing which includes at least two housing partsconnected to each other in the form of a diffuser bowl with outflowopenings toward the outside and a cover directly connected to thediffuser bowl. Inside the inflator at least a first and a secondcombustion chamber are provided, wherein the first combustion chamber isconfined by an inner wall and the second combustion chamber is locatedwithin the space confined by the diffuser bowl and the cover. Thediffuser bowl and/or the cover include a section that is reshaped, inparticular deep-drawn, into an indentation forming al least partially acircumferential section of the inner wall. Since the inner wallconfining the first combustion chamber is formed by the diffuser bowland/or the cover, a separate sleeve-shaped component part can be savedinside the inflator.

Preferably the first combustion chamber is surrounded al least insections, preferably completely, at least in the area of thecircumferential wall of the first combustion chamber by the secondcombustion chamber.

In accordance with a preferred embodiment, the housing parts are shapedso that they are connected to each other along an outer dosed curve andalong an inner closed curve, wherein the second combustion chamber isformed between the outer and the inner closed curve. In this way it ispossible, inter alia, that the second combustion chamber can have anannular shape and is confined by the two housing parts both at the outerand at the inner circumference.

At least one, preferably both curves can have a circular shape. In thisway the geometry of the inflator is simplified.

It is possible that the inner wall is mounted directly at the bottom ofthe opposed housing part. In this manner, the rod is realized by thedirect connection of the housing parts. Thus a separate element forminga tie rod can be saved and only one connecting point is required for thetie rod.

Preferably the inner wall is mounted directly at the bottom of theopposed housing part at the inner curve. In this way the tie rod iscombined with the design of the second combustion chamber.

The housing parts are preferably interconnected by welding, the weldsbeing located especially on the curves.

The indentation formed by reshaping and the first combustion chamberformed in this way is dosed, for instance, by a dosing member, the firstdosing member preferably forming a third housing part. This permits anindependent dosing of the first combustion chamber.

The dosing member preferably comprises one or more outflow openings forthe first combustion chamber, the one or more outflow opening(s) beingdirected especially towards the outer area and/or the inner area of theinflator. In this way separate outflow openings for the first combustionchamber can be provided.

Especially the housing part provided with the indentation has a bottomoutside the indentation and the dosing member is connected to the bottomand/or the outflow opening in the closing member is locatedsubstantially level with the bottom in this way a substantially uniformshape of the inflator is resulting without very distinct indentation orprojections in the area of the dosing member.

The first and second combustion chamber can be associated withrespective separate outflow openings, especially towards the outside.This permits an independent ignition of the two combustion chambers.

The outer housing preferably includes an axial central axis and theoutflow openings of the first combustion chamber are located moreclosely to the central axis by at least the factor 2 than those of thesecond combustion chamber. In this way the outflow openings of thedifferent combustion chambers are spatially separated from each other,thereby reducing the loads onto the component parts adjacent to theinflator.

The outer housing can have an axial central axis and the firstcombustion chamber can be arranged symmetrically with respect to thecentral axis. In this way loads onto the inflator housing aredistributed symmetrically.

In accordance with another embodiment, the outer housing includes anaxial central axis and the first combustion chamber is arrangedeccentrically with respect to the central axis. This is resulting, inthe second combustion chamber on the side of the central axis opposed tothe first combustion chamber, in an enlarged volume which may serve, forinstance, for attaching an igniter device.

Preferably the cover has a bowl shape. This permits a simple mode ofmanufacture, for instance by deep-drawing a sheet metal.

In accordance with a preferred embodiment, the housing part providedwith the indentation has a bowl shape. The indentation extends into theinterior of the bowl.

Advantageously the indentation can be formed in the bowl shape bydeep-drawing in two directions.

The invention moreover relates to an inflator comprising an outerhousing which has at least two housing parts connected to each other inthe form of a diffuser bowl with outflow openings and a cover directlyconnected to the diffuser bowl. Inside the inflator at least twocombustion chambers are provided with which separate igniting devicessituated in openings of the outer housing are associated. At least oneof the igniting devices is mounted to either of the two housing parts bya surrounding plastic injection molding. The fact that the ignitingdevices are mounted directly to either of the housing parts can save aseparate support for the igniting devices.

In accordance with a preferred embodiment, the surrounding plasticinjection moldings of the igniting devices are separated from eachother. This also permits separate mounting of the igniting devices.

In accordance with another embodiment, the plastic injection moldings ofthe igniting devices are interconnected. Thus the igniting devices canbe mounted to the inflator during a joint processing step.

Preferably, igniter plug receptacles exhibiting different geometries areformed in the plastic injection moldings. In this way, the differentigniter plug receptacles can be prevented from being confused.

The housing part can have at least one recess in the area of theigniting devices arranged at the outer housing, wherein contact pins ofthe igniting device extend preferably in the direction of the recess orin the opposite direction. Preferably the free ends of the contact pinsare located within the recess. The contact pins are thus protected frommechanical influence because the contact pins do not project from therecess into the open.

According to a preferred embodiment, the recess is lined at leastpartially by the plastic injection molding.

An igniting device associated with the second combustion chamber can bearranged in a separated area of the first combustion chamber. In thisway, both igniting devices can be arranged in the first combustionchamber, which is advantageous especially in a symmetric arrangement ofthe first combustion chamber.

Preferably the first combustion chamber is subdivided into two areasindependent of each other, separate outflow openings being associatedwith each area. This permits an independent ignition of the combustionchamber areas independent of each other and a different outflow path forthe gas generated in the combustion chamber area is permitted for eachcombustion chamber area.

The invention also relates to an inflator, especially in accordance withthe afore-described type, in which all outflow openings of a firstcombustion chamber are disposed in the outer housing such that they arelocated on one side of a first plane including an axial central axis ofthe outer housing. This permits spatial separation of the outflowopenings of the first combustion chamber.

The outflow openings arranged in the outer housing of the firstcombustion chamber are preferably located in a sector which is formed bythe first plane and a further second plane including the axial centralaxis, the sector having especially an angle of less than or equal to180°, preferably less than or equal to 135°, especially less than orequal to 90°.

Outflow openings of the second combustion chamber are arranged, forinstance, on a third plane substantially located perpendicularly to theaxial central axis.

The outflow openings of the first combustion chamber are preferablyarranged on a fourth plane arranged substantially in parallel to thethird plane including the outflow openings of the second combustionchamber.

The distance between the third plane and the fourth plane can be morethan 7 mm, preferably between 7 and 25 mm, further preferably between 11and 21 mm. In this manner, a spatial separation is possible in axialdirection of the discharge openings arranged in the third and fourthplanes.

Moreover, the invention relates to an inflator, especially as describedin the foregoing, comprising an outer housing which has at least twohousing parts connected to each other in the form of a diffuser bowlwith outflow openings and a cover directly connected to the diffuserbowl, wherein inside the inflator at least a first and a secondcombustion chamber are provided and the second combustion chamber islocated within the space confined by the diffuser bowl and the cover.The diffuser bowl forms a partition wall between the first and secondcombustion chambers. In this way a separate partition wall between thefirst and second combustion chambers can be saved.

Finally, the invention relates to an inflator, especially as describedin the foregoing, comprising an outer housing which has at least two.preferably exactly two housing parts connected to each other along acircumferential Sine in the form of a diffuser bowl with outflowopenings to the outside and a cover directly connected to the diffuserbowl. Inside the inflator at least two combustion chambers are providedwhich are associated with separate igniting devices. The diffuser bowland the cover separate the two combustion chambers from each other by atleast one common contact area spaced apart from the circumferentialline.

A module according to the invention comprises an inflator according tothe invention, an airbag inflatable by the inflator and a mounting meansfor attaching the module, especially in the interior of a vehicle.

The previously described second combustion chamber can be understood asmain combustion chamber of the inflator which can be ignited as thefirst one of the two combustion chambers. Staggered in time, thepreviously described first combustion chamber can then be ignited. Thetwo combustion chambers can Just as well be ignited in the inverseorder. Equally, both combustion chambers can be simultaneously ignited.Depending on the requirements of the vehicle occupant restraint system,the igniting times of the two combustion chambers can be adjusted toeach other.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention are resulting from thefollowing description and from the following drawings that are referredto, in which

FIG. 1 shows a section across an inflator according to a firstembodiment of the invention;

FIG. 2 shows a section across an inflator according to a secondembodiment of the invention having a dome-shaped closing member;

FIG. 3 shows a section across an inflator according to a thirdembodiment of the invention having a single recess in the cover;

FIG. 4 shows a section across the plane IV-IV of an inflator accordingto FIG. 2 or FIG. 3;

FIG. 5 shows a section across an inflator according to a fourthembodiment of the invention;

FIG. 6 shows a section across an inflator according to a fifthembodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 illustrates a first embodiment of an inflator 10 comprising anouter housing which has plural housing parts 12 connected to each other.A first housing part is a diffuser bowl 14 with outflow openings 16towards the outside and a flange 18 which serves for mounting theinflator 10 in an airbag module of a vehicle occupant restraint system.A second housing part 12 is a bowl-shaped cover 20 which at its outercircumference is connected by welding to the diffuser bowl 14 along anouter closed curve 22, the weld being located on the curve 22. The cover20 and the curve 22 have a circular shape.

The diffuser bowl 14 has a section 24 which is re-formed into anindentation extending into the interior of the inflator. The indentationis closed by a closing member 26 substantially level with the bottom ofthe diffuser bowl 14 partly forming the end face of the inflator 10,wherein the closing member 26 constitutes a third housing part 12. Thedosing member 26 is adjacent to the bottom of the diffuser bowl 14 andis connected to the diffuser bowl via a connecting point 28, e.g. bywelding.

The indentation in the diffuser bowl 14 and the closing member 26 definea cavity that forms a first, especially inner, combustion chamber 30.The first combustion chamber 30 is confined by an inner wall 32 formedby the diffuser bowl 14 in the section 24 of the indentation. The innerwall 32 extends to the opposite cover 20 and is mounted directly at thebottom of the cover 20 along an inner closed curve 34.

The curve 34 along which the inner wall 32 is mounted at the bottom ofthe cover 20 is preferably circular and constitutes a contact areabetween the diffuser bowl 14 and the cover 20. Also other, eveninterrupted, curved and/or segmented geometries, point or line contactareas are imaginable. A tie rod enhancing the stability of the outerhousing of the inflator is formed by mounting the inner waif at thebottom of the opposite housing part 12.

A first igniting device 38 is arranged in the first combustion chamber30 and extends through an opening of the diffuser bowl 14 and the cover20. The first igniting device is preferably fastened to the diffuserbowl 14 by a plastic injection molding 40. As an alternative, also forall other described igniting devices, a glass-metal seal can be providedas well.

A second combustion chamber 36 is located within the annular spaceconfined by the diffuser bow 14 and the cover 20. The inner wall 32forms a partition wall between the first and second combustion chambers30, 36 and is an integral part of the diffuser bowl 14.

A second igniting device 42 is associated with the second combustionchamber 36 and extends through an opening in the cover 20. wherein it isfastened to the cover 20 by a further plastic extrusion molding 40.

In the respective area of the igniting devices 38, 42 the cover 20exhibits s recess 44 into which the contact pins 46 of the ignitingdevices 38, 42 extend, wherein the free ends of the contact pins 46 arelocated within the recess and thus are protected from mechanical loads.The recesses 44 are lined at least partially by the plastic extrusionmoldings 40.

In order to prevent the connections of the two igniting devices 38, 42from being confused, the plastic extrusion moldings 40 are in the formof igniter plug receptacles having different geometries. In this way, anigniter plug is prevented from being connected to the wrong ignitingdevice 38, 42. Equally a third one and further connections, e.g. aground connection, can be provided. This is applicable to all describedigniting devices.

The first combustion chamber 30 includes first outflow openings 48extending in radial direction through the inner wall 32 and constitutinga connection of the first combustion chamber 30 to the second combustionchamber 36. Furthermore, the first combustion chamber 30 includes secondoutflow openings 50 extending in axial direction through the closingmember 26 and pointing to the outside.

It is possible, as a matter of course, that the first combustion chamber30 has outflow openings 48 only in the inner wall 32 or has outflowopenings 50 only in the closing member 26.

A first filter element 52 is arranged at the front face and ahead of theoutflow openings 50 provided in the closing member 26 and a secondfilter element 54 is arranged in the second combustion chamber 36 aheadof the outflow openings 16. The filter elements 52, 54 serve for coolingthe exiting gas and prevent hot particles from exiting the outer housingof the inflator 10.

The first combustion chamber 30 is preferably arranged asymmetrically inthe inflator 10 and eccentrically with respect to a central axis 66 ofthe inflator 10. By the eccentric arrangement of the first combustionchamber 30, at the right side of the inflator 10 in the shownembodiment, an enlarged volume which is used to arrange the secondigniting device 42 is resulting on the opposite side of the secondcombustion chamber 36.

An igniting sleeve 56 is disposed within the second combustion chamber36 above the igniting device 42 and serves for obtaining a homogenousignition in the second combustion chamber 36.

The first and second combustion chambers 30, 38 are filled with a firstfuel 58, wherein the nature (chemical composition and/or geometricshape) of the fuel 58 in the respective chambers can be either differentor identical. A second fuel 60 is provided within the igniting sleeve56.

The FIGS. 2 to 4 define first and second planes 72, 74 (cf. FIG. 4)including an axial central axis 66 of the outer housing of the inflator10 as well as third and fourth planes 68, 64 (cf. FIGS. 2 and 3) locatedsubstantially perpendicularly to the axial central axis 66.

FIG. 2 illustrates a second embodiment of the invention. The secondembodiment is largely analogous to the embodiment illustrated in FIG. 1,with corresponding parts being marked by equal reference numerals. Thesecond embodiment differs from the first embodiment by a modifiedclosing member 26 and modified outflow openings 50. Moreover, no outflowopenings 48 are provided in the inner wall 32 of the first combustionchamber.

The closing member 26 is L-shaped, wherein in a first area of the domethe first filter element 52 is arranged and in a second area of the domea cavity 62 is provided. From the cavity 62 outflow openings 50 extendthrough the closing member 26 in radial direction. The outflow openings50 in the closing member 26 are substantially level with the bottom ofthe diffuser bowl 14 in a fourth plane 64 located substantiallyperpendicularly to the axial central axis 66. The outflow openings 16 ofthe second combustion chamber 36 are arranged in a third plane 68located substantially perpendicularly to the axial central axis andbeing arranged substantially in parallel to the fourth plane 64. Theplanes 64, 68 are spaced apart from each other, the distance between theplanes being more than 7 mm or between 7 mm and 25 mm or between 11 mmand 21 mm.

FIG. 3 shows a third embodiment of the invention which is largelyanalogous to the embodiment shown in FIG. 2, with corresponding partsbeing marked by the same reference numerals. The third embodiment has acover 20 in which the first and second igniting devices 38, 42 arearranged in a joint recess 44. The plastic extrusion moldings 40 of theigniting devices 38, 42 are separated from each other in the shownembodiment. It is also possible, as a matter of course, that the plasticextrusion moldings of the two igniting devices 38, 42 areinterconnected.

The first igniting device 38 is fastened to the cover 20 by the plasticextrusion molding 40 in contrast to the afore-described embodiments.

FIG. 4 shows a section across the inflator 10 (a top view onto thesection across the plane IV-IV) according to the FIGS. 2 or 3. The firstfilter element 52 is removed in the view, whereby one can have a lookinto the first combustion chamber 30, especially onto the first ignitingdevice 38. The first combustion chamber 30 and thus the closing member26 are arranged eccentrically on the right side of the central axis 66.All outflow openings 50 are located in a sector which is formed by theplanes 72, 74 shown in dash-dot lines, the sector having an angle of135°. It is also possible that the sector has an angle of Jess than orequal to 180°, less than 136° or less than or equal to 90°. With anangle of 180° the planes 72, 74 coincide and all outflow openings 50 arelocated on one side of the plane. The outflow openings 50 of the firstcombustion chamber 36 are moreover closer to the central axis 66 by atleast a factor 2 than the outflow openings 16 of the second combustionchamber 36 (cf. FIG. 2 or 3).

The spatial separation of the outflow openings 16, 50 by a differentdistance from the central axis 66, the arrangement in different sectorsof the inflator housing or the spacing of the planes 64, 68 in which theoutflow openings 16, 50 are disposed reduces the load of the componentparts of the airbag module adjacent to the inflator 10, especially ofthe airbag.

FIG. 5 illustrates a fourth embodiment of the invention in which asection 24′ in the cover 20′ is re-formed into an indentation. In thiscase, too, corresponding parts again have equal reference numerals. Theindentation is closed by a closing member 26′ connected to the bottom ofthe cover 20′. A first igniting device 38′ and a second igniting device42′ are mounted to the dosing member 26′ by a, preferably joint, plasticinjection molding 40′. The plastic extrusion molding 40′ bundles twoigniter plug receptacles including contact pins 46′ which are located ina recess 44′ of the closing member 26′ and are configured analogously tothe afore-described embodiments. Also separate plastic injectionmoldings of the at least two igniters are possible.

The cover 20′ forms in the section 24′ an inner wait 32′ preferablyarranged symmetrically about a central axis 66′ of the inflator 10′. Theinner wall 32′ extends to the bottom of the opposite diffuser bowl 14′and is directly fastened there, preferably along an inner closed curve34′. Inside the indentation a cavity forming a first combustion chamber30 is defined by the closing member 26′.

An area 76 is separated from the first combustion chamber 30 by aseparating element 78. The second igniting device 42′ is arranged insaid separated area 76. Respective separate outflow openings 82 areassociated with the separated area 76 which connect the separated area76 to a preferably annular second combustion chamber 36′.

The inner wall 32′ forms a partition wall between the first combustionchamber 30 and the second combustion chamber 36′ in which outflowopenings 48′ are arranged so as to interconnect the two combustionchambers 30, 36′. The first combustion chamber 30 is thus divided intotwo areas 76, 30′ independent of each other, wherein different outflowopenings 82, 48′ are associated with each area. The diffuser bowl 14′includes outflow openings 16′ towards the outside.

Further component parts of the inflator 10′ such as e.g. fuel tablets,filter elements or combustion chamber closing elements are not shown inFIG. 5.

FIG. 6 illustrates a fifth embodiment of the invention in which aninflator 10 comprises a separate combustion chamber wall element 80which is connected on one side to the diffuser bowl 14 and on its otherside to the cover 20. The first igniting device 38 is mounted to thecombustion chamber wall element 80 via a plastic injection molding 40and a second igniting device is mounted to the cover 20 via a plasticinjection molding 40. A first combustion chamber 30 formed in the insideof the separate combustion chamber wall element 80 is connected to thesecond annular combustion chamber 36 through outflow openings 48.Further component parts of the inflator 10 are provided analogously tothe embodiment shown in FIG. 1.

1. An inflator, comprising: a diffuser bowl including an outer surface presented outside the inflator and an opposite inner surface; a cover directly connected to the diffuser bowl; and a closing member directly connected to the outer surface of the diffuser bowl, wherein: the outer surface of the diffuser bowl and the dosing member define a first combustion chamber, the inner surface of the diffuser bowl and the cover define a second combustion chamber, the closing member comprises outflow openings for discharging inflation fluid out of the first combustion chamber; and the diffuser bowl comprises outflow openings for discharging inflation fluid out of the second combustion chamber.
 2. The inflator according to claim 1, further comprising at least one actuatable igniting device mounted to the diffuser bowl by a plastic injection molding that extends through the diffuser bowl to an exterior of the inflator.
 3. The inflator according to claim 2, wherein the plastic injection molding extends through overlying portions of the diffuser bowl and the cover.
 4. The inflator according to claim 1, wherein a first igniting device is supported in the first combustion chamber by a first plastic injection molding that extends through the diffuser bowl to an exterior of the inflator, and a second igniting device is supported in the second combustion chamber by a second plastic injection molding that extends through the cover to an exterior of the inflator.
 5. The inflator according to claim 4, wherein the first plastic injection molding extends through overlying portions of the diffuser bowl and the cover.
 6. The inflator according to claim 1, wherein the diffuser bowl comprises a section that is shaped into an indentation, the indentation being covered by the closing member to define the first combustion chamber within the indentation.
 7. The inflator according to claim 1, wherein the first combustion chamber is surrounded circumferentially by the second combustion chamber.
 8. The inflator according to claim 1, wherein the diffuser bowl and the cover are configured so that they are connected to each other along an outer closed curve and along an inner closed curve, wherein the second combustion chamber is formed between the outer and inner closed curves.
 9. The inflator according to claim 8, wherein at least one of the closed curves has a circular shape.
 10. The inflator according to claim 8, wherein the cover is connected to the diffuser bowl along a bottom of the indentation.
 11. The inflator according to claim 1, wherein the inflator has a central axis and the outflow openings of the first combustion chamber are located more closely to the central axis by at least the factor of two than the outlet openings of second combustion chamber.
 12. The inflator according to claim 1, wherein all of the outflow openings of the closing member are arranged such that they are located on one side of a first plane including an axial central axis of the inflator.
 13. The inflator according to claim 12, wherein the outflow openings arranged in the outer housing of the first combustion chamber are located in a sector which is formed by the first plane and a further second plane including the axial central axis of the inflator, the sector having an angle of less than or equal to 90°.
 14. The inflator according to claim 1, wherein the outflow openings of the first combustion chamber are arranged in a first plane that extends perpendicular to a central axis of the inflator, and the outflow openings of the second combustion chamber are arranged in a second plane that is spaced from the first plane and extends parallel to the first plane.
 15. The inflator according to claim 14, wherein the distance between the first plane and the second plane is between 11 and 21 mm.
 16. A module comprising an inflator, an airbag inflatable by the inflator and a mounting means for attaching the module, especially in the interior of a vehicle, wherein the inflator is formed in accordance with claim
 1. 17. An inflator, comprising: a diffuser bowl comprising outflow openings for discharging inflation fluid out of the inflator; a cover directly connected to the diffuser bowl and defining at least one combustion chamber; and at least one actuatable igniting device, wherein the igniting device is mounted to the diffuser bowl by a plastic injection molding that extends through the diffuser bowl to an exterior of the inflator.
 18. An inflator comprising: an outer housing; a first combustion chamber defined by the outer housing and including one or more outflow openings for directing out of the inflator inflation fluid from the first combustion chamber, wherein all outflow openings of the first combustion chamber are arranged in the outer housing such that they are located on one side of a first plane including a central axis of the outer housing.
 19. The inflator according to claim 18, further comprising a second combustion chamber defined by the outer housing and including a plurality of outflow openings for directing out of the inflator inflation fluid from the second combustion chamber, wherein the second combustion chamber surrounds the first combustion chamber circumferentially, and wherein the outflow openings of the second combustion chamber are spaced circumferentially about the central axis of the inflator.
 20. The inflator according to claim 19, wherein the outer housing comprises a diffuser bowl including an outer surface presented outside the inflator and an opposite inner surface; a cover directly connected to the diffuser bowl; and a closing member directly connected to the outer surface of the diffuser bowl, wherein: the outer surface of the diffuser bowl and the closing member define the first combustion chamber, the inner surface of the diffuser bowl and the cover define the second combustion chamber, the closing member comprises the outflow openings for directing out of the inflator inflation fluid from the first combustion chamber; and the diffuser bowl comprises outflow openings for directing out of the inflator inflation fluid from the second combustion chamber.
 21. The inflator according to claim 20, further comprising at least one actuatable igniting device mounted to the diffuser bowl by a plastic injection molding that extends through the diffuser bowl to an exterior of the inflator. 